Some of the components (e.g., processors, micro-controllers, high speed video cards, disk drives, semi-conductor devices, and the like) of an electronic system (e.g., computer system, entertainment system, and the like) are known to generate relatively significant amounts of heat. The heat generating components, along with other components of the electronic system, are typically mounted on one or more printed circuit (PC) boards to thereby form a computer subsystem. Moreover, it is generally known that the performance and/or reliability of the components typically deteriorate as the temperature of the components increase. In an effort to improve the performance and/or reliability of electronic systems, they are typically equipped with a mechanism to provide a cooling fluid, e.g., air, flow through a housing surrounding the electronic systems to remove the generated heat. In these types of electronic systems, a fan or blower directs a tangential flow of cooling fluid across the PC board and heat sinks to cool the components by convection.
Dissipating the heat generated by these components becomes ever more difficult as the electronic systems incorporate greater numbers of components. By way of example, some high-end servers can house as many as 64 microprocessors, with associated memory devices and ASICS, dissipating up to 20 kilowatts. Conventional cooling systems may be unable to adequately cool these types of electronic systems. For instance, the cooling fluid flow across a PC board may be relatively impeded by installation of the additional components blocking the fluid flow.
In addition, the tangential, unidirectional nature of the fluid flow as the number of components increases as well as the number of the subsystems, typically causes the multiple components to be cooled in series. As a consequence, the cooling fluid flow may be a few degrees warmer than expected, thus causing components located relatively downstream to be cooled less than expected. This drawback may be somewhat alleviated by using a high fluid flow rate and by using heat sinks having a relatively large surface area. The large bulk volume flow can also require the use of several blowers and relatively large exhaust ducting. The resulting size and complexity of these types of cooling systems have substantially detracted from their commercial viability, e.g., by adding additional costs to the overall electronic systems. In addition, the use of additional blowers generally increases the amount of energy and/or the space required to operate the cooling systems, thereby increasing the operating costs.
In addition, various components in electronic systems typically generate various amounts of heat and thus require various levels of cooling. Conventional cooling systems are typically operated in a substantially uniform manner, regardless of the level of heat generated by the individual components. By way of example, conventional cooling systems are generally designed to operate according to a worst-case scenario. That is, cooling fluid is supplied to the components at around 100% of the estimated cooling requirement. In one respect, conventional cooling systems often attempt to cool components that may not be operating at a level which may cause its temperature to exceed the predetermined temperature range. Consequently, conventional cooling systems often incur a greater amount of operating expense than is necessary to sufficiently cool the heat generating components.